Antipodean and Northern European drummers are the focus of these essays in solo percussion. But the sociology of why these particular stick men should choose to go it alone is not part of this study. What is generic is how similarly — and how differently — six improvisers choose to pursue a solo course.

If theres one process in common, its that all add a physical codicil to their regular kit. Thus, whether they say so or not, it appears as if some sort of electronic interface meets the trap set. Most open about it are Amsterdam-based, Melbourne-born Steve Heather — featured on Berlin Drums — and Norwegian Ingar Zach. Heather, who often works with keyboardist Cor Fuhler and reedist Jorrit Dijkstra, uses a sampler as well as found percussive objects, while Zach — who plays with everyone from Swiss violinist Charlotte Hug to British guitarist Derek Bailey — extends his drums and percussion with gongs, motors and a zither.

Berlin-based Eric Schaefer, an Eno look-alike who has worked with the chamber ensemble Camera Obscura as well as with jazzers like reedist Gebhard Ullmann, also relies on the zither for extra timbres. Meanwhile Will Guthrie, who still resides in Heathers hometown, features motor-based toys and machines plus electronics in his improvisations. Only Burkhard Beins, the fourth participant in Berlin Drums, who collaborates with guitarist John Bissett and Keith Rowe; and Aussie in Berlin, Tony Buck known for his work with The Necks, claim they limit themselves to acoustic objects that can be hit.

Appreciation for the end result can also be limited by length, and here Zach is at a disadvantage. His recital, recorded live in an abandoned Oslo chocolate factory lasts almost 44 minutes. Guthries combination of live and studio tracks is longer, but divided into three parts. Meanwhile each Berlin drummer is showcased on a separate three-inch mini-CD, the longest of which reads out at less than 22 minutes.

Perhaps to overcome this perceived attention span demand, the Oslo-resident introduces as many different tones and timbres as he can and only gradually augments his sounds from indistinct rumbles that result from the kit moving along the tattered floorboards to stentorian rain storm and grinding industrial replications.

Following the creation of a tugboat whistle by gliding a stick along a snare top, cymbal shimmers and rolling metallic screeches enter the soundscape. Oscillating cathedral organ-like tones mix with approximation of bells pealing as looping sine waves — sounding somewhat like a mini dust buster — make their presence felt. Soon you can make out other percussion entries real and imagined. Theres what could be the swish of a swizzle stick and the vibrating friction of a glass armonica. Cymbals are rapped and zither strings resonate. Then what could be the rumble of thunderclouds becomes louder and more threatening. After the storm subsides into press rolls, a single thwack on a cowbell plus melodic xylophone or glockenspiel inflections appear.

All the while, a hypnotic, electro-acoustic drone, sort of like what the band AMM produces, comes in and out of focus; sometimes in front of the other instrumental sounds, sometimes just behind them. Other reverberations include a gong smash that would impress J. Arthur Rank, a shrill whistle, sharp knife stropping and wooden thwacks on drum rims.

Are the motors creating what could be inside piano rumble mixed with jackhammer tones? And when this timbre quickly gives way to diffuse vibrations from other parts of the kit, and are succeeded by a crescendo of motorized tones should you link the sound to what youd hear from the assembly line of a sawmill or other heavy industrial outlet? Introducing a touch of primitivism, abrasive ratchet and woodblock scrapes are subsumed by the diminuendo of the lockstep motor, with the performance ending as wetted fingers stroked on a taut drum skin create faux Swiss alp horn tones.

Guthrie, who is also involved in dance, film, theatre and jazz projects, creates a similar panoply of real and imagined sounds on the two longer tracks of his CD.

The more than 22-minute Westspace, done live, finds similar electronic drones throughout. Beginning with creaking door squeaks and bell-like ring modulator input, hes soon mixing regular paradiddles, ruffs and flams on the snares and tom toms with bounce pressure on what sounds like tam tams, gongs and a bell tree. Using loops to make the bell ringing more clangorous and insistent, he ends up with an aural percussion picture midway between the vibrations from Roscoe Mitchells percussion cage and the resonation from Ellen Fullmans bronze wire long string instrument. Slapping away the ultimate reverb, the piece dissolves into silence.

A similar AMM-influenced electronic wash covers the 19½-minute Blanket where the buzzing drone from a ride cymbal is extended with sampling and vibrating loops. Not only does a spinning wheel of flanged metallic tones meet a resonating drum beat, but the thunder storm, turbo accelerations and cathedral bell ringing seems to have migrated over from Oslo to Melbourne. However, the concluding manipulations bring the sounds of scraped and gyrating items on an immovable surface, upfront.

Guthries homeboy Heather has a completely antithetical approach to the others conceptions. His Electric Bongo Bongo features a near hand-clapping beat with enough bass drum accents to move into a disco. The rhythmically powerful sampled beats arent that simple however, since they have to vie for aural space with what sounds like tambourine oriented reverb, burbling dentist drill drones and other tones that resemble paper being crumbled, drum top cleaning cloth echoing swipes and raps on the wooden sides of the kit.

In contrast Aussie-turned Berliner Buck turns out the most dissonant, yet individualized program in his one-second-over-21-minute disc. His European residency has resulted in close associations with unique sound seekers like German minimalist trumpeter Axel Dörner. Melding scraped ratchet or güiro timbres with the undertow of electronic buzzes, it appears hes scratching and shifting all sorts of items along and over the sides and tops of the drums.

The only drummer here who seems to vary his drum beats with cross sticking, at points he doubles the tempo and uses the bass drum punch as punctuation. When hes not exploring its sections as if he was loosening and tightening the connectors in his kit as he plays, he could be dropping and picking up chains, rotating them on drum tops and using the top of a drumstick to scratch out elephant trumpeting tones on a cymbal. Building up to locomotive-like blaring, he uses mallets and sticks to eventually resonate individual kit parts, letting the natural vibrations serve as a climax and coda.

Dividing his contribution into seven sections gives Schaefer more improvisational scope, yet most of the time his pitter patter paradiddles, snare rat tats and cymbal buzzes arent that different from what the others create. Ingenuity is most apparent on the three-part Dont tell Morton. Here his combination of zither and percussion manages to produce celeste-like, high-pitched plucked textures. Further on, what could be keyboard manipulated church bells resonate in tandem with wooden stick reverberations and the splish splash on cymbal tops.

Beins oddly titled Nadir begins inventively as a thin midst of cymbal drizzle commingles with flutters of sequenced sounds. He too appears to be tossing percussive items on the floor, at least until a feedback-rich electrical outlet sound interrupts the impulse. Shrilled sequencer timbres get louder in the penultimate moments, cutting in and out of the watery drumbeats. Coda is the sound of small bell repeatedly tinkling.

Six percussionists, six ways of handling the kit, and all worth examination should new approaches to the drum set hit it off with your listening program.